The process most used for the production of hydrogen on an industrial scale is steam reforming. This is a process with several steps with different operating conditions and catalysts. In the step called “steam reforming”, which uses catalyst of the nickel type on refractory supports, such as alumina, calcium aluminate or magnesium aluminate, the main reactions that occur are:
CnHm + n H2O → CO + (n + m/2) H2ΔH0298 < 0 CH4 + H2O → CO + 3 H2ΔH0298 = + 206.2 kJ/mol  CO + H2O → CO2 + H2ΔH0298 = − 41.2 kJ/mol
The raw materials used for the steam reforming process are natural gas, refinery gas, propane, butane, liquefied petroleum gas or naphtha.
The use of renewable raw materials (biomass), such as ethanol, for the production of hydrogen will make it possible to reduce the emission of CO2 in the overall balance, since these raw materials fix CO2 from the atmosphere. Despite the environmental benefits, the technology for the large-scale production of H2 from ethanol has not yet been consolidated technically.
Deactivation of the catalysts used in the steam reforming process by the formation of coke is the main difficulty to be solved, to make the production of hydrogen from ethanol industrially viable. Ethylene formed from the dehydration of ethanol is one of the main compounds promoting coke formation in the steam reforming of ethanol. In an industrial unit for steam reforming from natural gas or refinery gas, the maximum ethylene content considered to be permissible in the feed is around 1% v/v. Above this value the loss of activity of the catalysts makes the process economically unviable.
One technical solution that is being investigated is the development of catalysts that are more resistant to deactivation by coke deposition. Some of the types of catalysts investigated are: oxides and mixed oxides such as MgO, Al2O3, V2O5, ZnO, TiO2, La2O3, CeO2, Sm2O3, La2O3—Al2O3, CeO2—Al2O3, MgO—Al2O3; supported Co such as Co/Al2O3, Co/La2O3, Co/SiO2, Co/MgO, Co/ZrO2, Co/ZnO, Co/TiO2, Co/V2O5, Co/CeO2, Co/Sm2O3, Co/CeO2—ZrO2, Co/C; supported Ni such as Ni/La2O3, Ni(La2O3—Al2O3), Ni/Al2O3, Ni/MgO, Ni—Cu/SiO2, Ni—Cu/Al2O3, Ni—Cu—K/Al2O3; Cu supported on Nb2O5—Al2O3 and on ZnO—Al2O3; supported precious metals such as Rh on TiO2, SiO2, CeO2, ZrO2, Al2O3, MgO and CeO2—ZrO2, Pt on CeO2, Pd on CeO2, Al2O3 and C; metal alloys such as Rh—Au/CeO2, Rh—Pt/CeO2 and Pt—Pd/CeO2.
However, these catalysts still have limitations for industrial use, such as: they do not have sufficient resistance to deactivation by coke formation or sintering of the active phase; they are expensive as they are based on precious metals or they form by-products, such as acetaldehyde, acetates, acetone and ethylene, which make it difficult to purify the hydrogen (or the synthesis gas) produced or cause difficulties and/or additional costs due to contamination of the condensate generated in the process from the water used in excess of the stoichiometry of the reaction.
A second technical solution, and the purpose of the present invention, would be prior conversion of the ethanol to raw materials used industrially, which converts the ethanol to a gas rich in methane and free from olefins and other organic contaminants, such as acetaldehydes, ketones, acetates and others, by combining process conditions and suitable catalysts that give low coke formation. This gas can then be used as feed for a conventional unit for production of hydrogen that uses natural gas, liquefied petroleum gas, refinery gas, naphtha or combinations thereof, as raw materials.
The production of hydrogen by steam reforming of ethanol can be presented by the following reaction:C2H5OH+3H2O→2CO2+6H2 
In practice, various other reactions may occur, depending on the type of catalyst and the operating conditions used, such as:
a) formation of ethylene by the reaction of dehydration of ethanol.C2H5OH→C2H4+H2O
b) formation of acetaldehyde by dehydrogenation of ethanol.C2H5OH→C2H4O+H2 
c) decomposition of ethanol and the reaction of steam reforming of ethanol or of intermediates producing CO, CO2 and CH4.C2H5OH→CH4+H2 C2H4O+H2O→CH4+CO2+H2 C2H4+H2O→CH4+CO+H2 C2H4+2H2O→CH4+CO2+2 H2 
Catalysts containing precious metal tend to have greater resistance to coke formation than the equivalent catalysts using nickel as the active phase. However, their costs of production are higher, which tends to make their industrial use unviable. Accordingly, although they have been known for a long time, these catalysts based on precious metals have not found industrial application in large-scale production of hydrogen.
Industrially, the catalysts used for the production of hydrogen from natural gas, propane, butane, liquid petroleum gas, refinery gas or naphtha, in units of large capacity (defined here as having a production capacity above 10 000 Nm3/day), comprise nickel supported on refractory materials, such as: alumina, calcium aluminate or magnesium aluminate, and can be promoted with other elements, such as alkali metals (especially potassium) and rare earths (especially lanthanum).
Nickel-based catalysts can suffer serious deactivation by coke formation when used for the steam reforming of ethanol, the rate of coke formation depending on the type of catalyst and the operating conditions.
The catalyst of the Ni/Al2O3 type displays good activity and selectivity for the production of hydrogen at temperatures above 550° C. At lower temperatures, ethylene can be obtained, accompanied by rapid loss of activity associated with the deposition of coke.
The tendency for coke formation, on supported nickel catalysts, in the steam reforming of ethanol is well known. Sun and co-workers report in the publications J. Sun, X. P. Qiu, F. Wu, W. T. Zhu, “H2 from steam reforming of ethanol at low temperature over Ni/Y2O3, Ni/La2O3 and Ni/Al2O3 catalysts for fuel-cell”, International Journal of Hydrogen Energy 30 (2005) 437-445 and J. Sun, X. Qiu, F. Wu, W. Zhu, W. Wang, S. Hao, “Hydrogen from steam reforming of ethanol in low and middle temperature range for fuel cell application”, International Journal of Hydrogen Energy 29 (2004) 1075-1081 that have used catalysts of the Ni/Y2O3, Ni/La2O3 and Ni/Al2O3 type. The authors taught that the use of supports that are free from acidity, at temperatures above 380° C., reduces coke formation.
The invention described in WO 2009/004462A1 teaches producing hydrogen and carbon nanotubes (a special type of coke) from the decomposition of ethanol on nickel-based catalysts supported on lanthanum.
The results disclosed show that the performance of nickel-based catalysts, for the production of hydrogen from ethanol, is applicable to existing industrial units for production of hydrogen, but can be improved further. A technique described in the literature for the production of hydrogen from ethanol, called autothermal reforming, involves addition of oxygen to the mixture of ethanol and steam.
WO2009/009844A2 teaches the addition of oxygen in the feed of ethanol and steam, associated with the use of special catalysts, based on cerium oxide, with promoters selected from the group comprising alkali metals and the lanthanides, for the production of H2 from ethanol.
Another example of this technology is described in US2005/0260123A1, which teaches a process for producing hydrogen, by the use of catalysts that comprise Rh on supports, such as cerium oxide, and is carried out in autothermal conditions with introduction of oxygen into the reaction gas.
Although the use of oxygen in the feed has advantages, such as supplying the heat of reaction through reactions of combustion, and assisting in the removal of the coke deposit on the catalyst, it is not a practical method for the large-scale production of hydrogen, owing to the cost associated with the production of oxygen and purification of the hydrogen, when using air in place of oxygen. This method would be difficult to apply in existing industrial units for production of hydrogen by steam reforming, owing to the high capital expenditure required for equipment modification.
A possible technique for the production of hydrogen from ethanol would be its prior conversion to raw materials that are already used for large-scale production of hydrogen, such as naphtha, natural gas or light hydrocarbons, methane, ethane, propane and butane. After a first step of prior conversion of ethanol, the hydrocarbon stream would feed a conventional process for production of hydrogen, where the hydrocarbons would be converted to a mixture of H2, CO, CO2 and residual methane. In the end of the process, the H2 (or the H2/CO mixture if desired) would be purified by conventional techniques of absorption on amines or by means of PSA—pressure swing adsorption.
The US2006/0057058A1 teaches a method for the production of hydrogen-rich gas from ethanol characterized by:                a) a first step in which ethanol, steam and recycle hydrogen feed a reactor, where the catalytic steps of dehydrogenation of ethanol to ethylene and of hydrogenation of ethylene to ethane take place, wherein the catalyst comprises Pt, Pd or Cu on a support selected from the group comprising alumina, silica-alumina, zirconia and zeolites, in particular zeolite HZSM5;        b) a second step of adiabatic pre-reforming wherein the ethane-rich stream is transformed to a methane-rich stream;        c) feed of the methane-rich stream in a typical configuration of industrial units for steam reforming, containing a primary reformer and a reactor.        
The invention does not report data on the stability of the catalysts. The hydrogen produced in accordance with this invention supplies a fuel cell and is therefore suitable for small-scale use.
WO2009/130197 discloses a method for the conversion of ethanol to methane, in a pre-reformer. According to the method, ethanol and steam are reacted on a catalyst that comprises platinum on a support of ZrO2 and CeO2, in the temperature range from 300° C. to 550° C.
The work by S. Freni, N. Mondelo, S. Cavallaro et al., React. Kinet. Catal. Lett, 71 (2000) 143, describes the use of a first step of conversion of ethanol to acetaldehyde, in the presence of steam and hydrogen, on a catalyst of the Cu type supported on silica, at temperatures between 300° C. and 400° C., followed by the reaction of steam reforming of the reaction mixture on a catalyst of the Ni type supported on magnesium oxide.
The specialized literature also teaches a two-stage processes for the production of hydrogen from ethanol. However, these processes have drawbacks, related to the use of noble metals catalysts and of the production of intermediates. These lack of experience on their impact on the performance of the usual catalysts for steam reforming, hence tests are required for evaluating the durability of the catalytic systems and their applicability in existing units.